Infant mortality among subsequent siblings of infants who died of sudden infant death syndrome.

A specially designed method for measuring infant mortality among families with subsequent siblings of sudden infant death syndrome (SIDS) victims in the state of Washington, 1969 to 1984, yielded results similar to those from an earlier study in Norway. In both studies the SIDS rates among siblings were substantially lower than prior estimates. The rate of SIDS in siblings of infants who died of SIDS did not differ significantly from the SIDS rate among control infants matched for maternal age and birth order. Total infant mortality rates in the two groups were virtually identical. From the data at hand, it appears that earlier estimates of the risk of SIDS in siblings were inflated and that parents of SIDS victims can be counseled accordingly.